DESCRIPTION: (Applicant's Description) The goal of this SBIR application is to develop [1-123]-labeled sigma-2 receptor imaging agents for Single Photon Emission Computed Tomography (SPECT) studies of breast cancer. This approach is based on the observation that sigma-2 receptors are expressed in high density in a number of human tumors, including breast tumors. Our preliminary data also indicate that [1-123]-labeled sigma-2 receptor imaging radiotracers can not only be used in the anatomical imaging of breast tumors, but may also provide information regarding the proliferative status of breast cancer. An additional incentive for focusing on sigma-2 receptors stems from our development of a number of new sigma-2 selective compounds that will serve as lead compounds for SPECT radiotracer development. There are currently no sigma-2 selective radiotracers for SPECT imaging studies of breast cancer. The strategy chosen for incorporating [1-123] into the promising compounds will use established methods developed for making [1-123]-labeled receptor imaging agents. Although the proposed radiopharmaceuticals will initially benefit the diagnosis and treament of breast cancer, we believe the technology developed in this SBIR application will translate to other human cancers (lung carcinoma, gliomas, etc.) that possess a high density of sigma-2 receptors. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE